8.5
Application of a handheld laser wind sensor to provide instantaneous wind profiles in operations with very short lead-times

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Wednesday, 26 January 2011: 4:45 PM
Application of a handheld laser wind sensor to provide instantaneous wind profiles in operations with very short lead-times
307-308 (Washington State Convention Center)
Christopher D. Bedford CCM, Sailing Weather Service, LLC, Watertown, MA; and D. B. Dakin

Real-time boundary layer wind observations are critical to success in many so-called “short-fuse” operational activities which require immediate decisions based upon limited, but directly related data. For example, three-dimensional boundary layer wind structure is a first-order input for wind turbine control systems, hazardous pollutant release mitigation and public protection, aircraft takeoff/landing activities, port loading/unloading operations, weapons firing systems, and fertilizer application by aircraft, to name just a few.

Many existing laser wind sensors/profilers are designed to average winds over time windows of 5, 10, 15-minutes and are frequently limited to vertical profiling with no horizontal wind field assessment. However, there are applications which require immediate and instantaneous action at time shorter time scales than what averaging can provide. This is especially true during, for example, rapid wind speed ramp events around wind turbines or very short-term, reactive wild fire management or emergency responder deployment. Many existing laser systems are relatively large and require some planning, siting, and preparation prior to deployment in the field.

Recent advancements in laser wind sensors now permits instantaneous measurement of wind speed and direction at a distance from the instrument itself. Miniaturization, reduction in power consumption, and software efficiencies are making these sensors more flexible, transportable, and easily deployed in the field by users with only basic skills in the use and operation of the systems.

Recently, an opportunity arose to demonstrate new laser wind sensing technology in a unique operational decision-making setting during the 33rd America's Cup yachting regatta. The America's Cup is the world's premiere yacht racing event where instantaneous wind measurements are used in combination with very-short term predictions to decide tactical maneuvers which will lead to victory.

In yacht racing, advantage is gained by placing the yacht in the most optimum place relative to the wind such that benefit is gained over the position of one's opponent(s). This is particularly true in match racing (only two competitors) where immediate advantage can be gained in the first few hundred meters of a race such that the following boat can be “controlled” and often prevented from passing. Because of the importance of this initial advantage, competitors focus on observing and predicting a so-called “first wind shift” – the initial change in wind and/or speed within the first 1- to 5-min (< 1km) of the race.

In previous America's Cup races, competitors have used instrumented boats and weather buoys on the race course to detect changes within the first kilometer or so of the race. However, there is a practical and cost limitation to putting enough instrumentation on the race course to properly define what can ultimately be relatively small changes in wind speed and direction necessary to define the “first wind shift” and then seize advantage from the competition.

In late 2009/early 2010, the sole American team competing to win the America's Cup – BMW Oracle Racing – entered into an agreement with Catch the Wind, Inc. to employ a new portable laser wind sensor called Racer's Edge. The portable sensor uses a pulsed laser to measure 3-D wind speed and direction at three range gates in any direction the sensor is pointed by the user. Maximum range is 1 km. In horizontal mode (controlled by the direction the user is pointing the instrument) winds were measured at range gates positioned 400m, 700m, and 1000m from the observer. If desired, the observer could direct the laser at an angle above the horizontal and obtain vertical wind profile information (automatically calculated with an internal compass and angle sensor).

This presentation will provide an overview of the Racer's Edge laser wind sensor, discussion of comparison with more traditional buoy and boat-based measurements, and application of the collected data to the detection of the “first wind shift” for competitive advantage in high performance yacht racing.